This is it, there are so many facets to this case.
I have actually heard that she DID have music playing, and Sion said he had turned it down, yet denied having seen Billie when he did so (unlikely-sounding, given that she was painting the patio doors to the room the music would have been playing in, however).
And yes, there are many reports - and confirmed by Lois, his wife, and neighbours - that Billie had feared having been stalked, as well as there having been prowlers in the neighbourhood, and even their garden, as well as, albeit from Sion, of someone staring intently at their house. This strange, highly disturbing behaviour could well have been part of a lead-up for someone to do something very bad to Billie.
I have also heard convincing rebuttals of two points for the 'prosecution', namely that he took a long route to the Do It All, and that he went to a place that wasn't the closest shop to buy white spirit from.
Someone from Hastings has said that Lower Park Road, where they lived, was a road almost impossible to do a three-point turn on; so going the long way round could be something he always did.
Regarding the choice of shop, the Do It All had free parking, whereas the other shop apparently didn't have plentiful parking spaces in its vicinity, and parking charges could have applied; I often use stores further away, on this basis.
Additionally, the prosecution claimed that being aware of the opportunity to access Billie on her own was unlikely. However, given that they lived opposite a park, I say it wasn't. Living opposite a park can make for a lovely view, but, as someone who lives opposite a park, it can have its downsides, even in a nice area. Although it's not on the scale of MURDER, my house has had youths throwing apples at its windows, and there is often drug-taking going on, and mentally unwell people about.
A person so inclined - and Billie had reported being stalked - could easily keep watch from the park, and wait until he'd seen everyone else he knew to be living in the house, go out. Although he likely wouldn't know that she was actually outside, on the patio, he could have been aiming to break in and kill her - who knows?
I do admit that Sion sitting in his car, waiting for the ambulance seems suspect, and quite possibly a likely tactic to explain any blood droplets found later in the car. On the other hand, he could quite possibly have wanted to ensure that the ambulance found the right house, and might have found that waiting in his car gave him that tiny bit more privacy at a distressing time, than standing on the pavement, on a busy road, would have done. That said, didn't he actually claim it was to put the roof of the car up? God, this case makes one's head hurt!
I would still love to know more about the dismissed witness statement of someone covered in blood and paint reported to have been seen running in the area. If this IS true, than there's surely no doubt that it was that person, rather than Sion; how many people does one tend to see, running around covered in blood and paint???